What Grows There :: Hugh Conlon, Horticulturalist, Garden Advisor, and Photographer

10 Winter Care Tips For Landscape Plants

Posted by Hugh on October 10th, 2015

Recently pruned roses and winter-protecting mulch

Recently pruned roses and winter-protecting leaf mold compost

Do Not Plant Chaste tree (Vitex) in Autumn in zones 6 and 7

Fall-planted perennials, shrubs and trees need some additional attention. Here are 10 basic tips to help plants get past potential winter woes:

Select balled-and-burlapped (b&b) or container-grown plants rather than bare-rooted stock. Most bare-root plants are planted in late winter or early spring when plants are still dormant.
Evergreens, particularly broad-leaved evergreens, are more susceptible to winter dryness because leaves lose more water than narrow-leaved evergreens and deciduous plants. Roots may not replace moisture loss in frozen ground.
Don’t delay planting landscape plants you found on sale at local garden centers at deep discounted prices. Early fall planting ensures good root development.
To Mulch or Not? A 2-4 inch layer of mulch can prevent wide soil temperature fluctuations. Do not mulch newly set fruit trees which may attract overwintering voles and rabbits that feed on their tender sugary bark.
Plant ground covers and shallow-rooted shrubs earlier in fall to avoid heaving out of the ground by alternate freezing and thawing. A 2-4 inch layer of mulch by late November or early December to reduce wide soil temperature fluctuations.
Particularly in northern areas, insulate rose crowns and roots with 4-6 inches of loose non-packing organic mulch such as straw or oak leaves.
Plant bulbs when there is a chill in the air or after first killing frost. In southern areas (zones 6 – 8), garden centers are lowering prices in November to make room for winter holiday inventory.
Cover the trunk of thin-barked young trees with paper wraps in late November to prevent winter frost cracks, sunscald, and deer and rodent damage; remove all wraps by early May.
In most regions prune on the “downside” of winter in March and early April. Choose a comfortable day so to avoid mistakes made in a hurry. In zone 6 marginally hardy shrubs include roses, bigleaf hydrangeas (H. macrophylla), crape myrtles, and chaste trees (Vitex spp.).
Don’t forget to move semi-tender plants in containers into an unheated garage or greenhouse for winter protection. Minimum day/night temperatures should not drop below 40 °F.

Ripening Tomatoes Off The Vine

Posted by Hugh on October 7th, 2015

Ripening Tomatoes on the vine

The threat of freezing temperatures in the fall has gardeners scrambling to harvest all green tomatoes that may be a few weeks away from regular harvest. You may opt to prepare fried green tomatoes or to ripen the fruits indoors, still a tastier alternative to store-bought tomatoes.

Pick green tomatoes that show a tinge of color at the blossom (bottom) end and feel a little softer than hard dark green fruits. Remove twigs, stems, leaves etc. that could rub or damage the skin during storage.

Inspect all fruits for decay or mold and immediately discard all bad ones. The cooler the storage area for the tomatoes, the longer the ripening process will take.

Tomatoes ripen naturally on the kitchen countertop away from direct sunlight and extremes of heat and cold; set fruits on their shoulders rather than on their blossom ends. Another popular technique is to ripen green tomatoes in a plastic or paper bag, or wrap each in newspaper and store in an enclosed plastic or cardboard box. Allow 7-14 days for ripening at home room temperature. Some long-keeping tomato varieties may take longer.

To speed the ripening process, add slices of ripe apples or bananas; ripened fruits naturally release ethylene gas. Skin color (red, pink, purple or yellow) changes occur several days earlier by this method. Peek inside the container every 2-3 days. Trucking companies often utilize ethylene gas to ripen early-harvested tomatoes, bananas, pears and other orchard grown fruits en route to the supermarket.

Green tomatoes can be fried, as in “fried green tomatoes”, or pickled, made into salsa, green tomato jam, soups, green ketchup, and added to pasta sauces.

Paint and Wrap Newly Set Peach Tree Trunks

Posted by Hugh on October 4th, 2015

The bark of young peach (Prunus persica) or nectarine (P. persica nucipersica) trees are sensitive to winter injury caused by rapid drops in daily temperatures. On a winter’s day, the sun may heat up the sapwood under the thin skinned peach bark. Research in Georgia shows that temperatures on the south side of a peach tree may reach 96 °F while the outside air temperature is only 55°F.

Sapwood thaws and refreezes, possibly injuring tissues beneath the thin bark. The south side of the trunk warms more than north side; freeze injury and bark splitting are generally worse on the south side. White latex paints offers some winter protection by reflecting heat and light away. Daily winter temperature gradients are less on the painted trunks compared to untreated.

Painting is most effective on 1-2 year old peach and nectarine trees. Apply one coat of a water-based interior white latex paint to trunk and main branches from 2 ½ feet high down to the ground. Dilute the paint at least 50% with water to allow the trunk wood to breathe. Never apply an oil-based paint to a tree trunk and branches.

One more chore: protect trunk of young 1-2 year old fruit trees against gnawing rabbits and field mice (voles). Loosely wrap chicken wire or wire mesh cloth for protection, and permit the trunk room to expand and breath. Do not wrap with plastic film or piping as this creates a winter haven for insects and other critters. Remove all protection guards once trees have started their third spring.

Photo credit: Dr. David Lockwood, Tree Fruit Specialist, University of Tennessee, Knoxville..

Foxtail Lilies Are Uniquely Different

Posted by Hugh on October 2nd, 2015

Foxtail Lilies at Chanticleer, Wayne, PA

Foxtail lilies or desert candles (Eremurus spp.) are beginning to find an audience with U.S. gardeners. Foxtail lilies are indigenous to the grasslands and semi-arid parts of Iran, Turkey, and Afghanistan (USDA hardiness zones 5–8).

Tall spires of brightly colored flowers emerge in late spring; small individual flowers are densely packed together. Each showy flower cluster can take up half of the plant’s tall stem. Flowers begin opening at the bottom of the stalk and progress upward. Colors range from white, yellow, orange and red shades.

Low mounds of grass-like leaves emerge in early spring from hardy tubers. Depending on variety, they can rise three to eight feet tall. The mound of foliage is typically covers 1-2 feet in ground width.

This herbaceous perennial thrives in full sun, and is best adapted to a moist, compost-rich, well-drained sandy soil. The Achilles heel of foxtail lilies is poor soil drainage. Adding 1-2 handfuls of Permatil® beneath each tuber at planting time prevents root rot problems and potential infestations by voles. It is exceptionally drought tolerant and requires some protection from wind.

In early autumn tubers should be planted shallowly (2 to 4 inches deep) immediately after arrival from the nursery. Do not allow tubers to dry out and do not disturb them once planted. These woody, tuberous rootstocks should be planted upon receipt 36 inches apart and never overcrowd them. Mulch the soil over winter for additional winter protection.

Should You Plant In Fall?

Posted by Hugh on September 30th, 2015

Magnolias Better Planted In Spring

Mahonia bealei better planted in spring

Should you plant in the Fall? It depends what region you live in, what month in fall, and what species you’re planting. If you live in the mid-Atlantic, coastal New England, or Southeastern U.S., fall is an excellent time to set most hardy plants. Most (not all) trees, shrubs, perennials, and spring flowering bulbs can be planted fall. Across the northern U.S. and central Canada, winter arrives early. In the southeastern U.S., you may plant safely through Thanksgiving Day.

Why plant in the fall:

Soils are warm, moderately moist, and easy to dig in.
Planting weather is mild and it is usually comfortable to work outside.
Pests, diseases, and weeds are less active in fall and little threat to new plants.
Deciduous species are dropping their foliage and gives roots time to establish before next summer. Roots actively grow in soil above 40 ºF. Winter temperatures will ensure great blooms next spring.
Apple and pear trees can be planted, but wait on cherry, plum and peaches. Protect around tree’s tender bark with chicken wire to guard against rabbit and vole injury.
An ideal time to plant spring flowering bulbs such as daffodils, tulips, hyacinths, and many more.

What NOT to plant in fall:

Shrubs like roses and bigleaf hydrangeas (H. macrophylla).
Some perennials such as sage (Salvia spp.), cranesbill (Geranium spp.), and coneflowers (Echinacea spp.).
In northerly areas (zone 5 and colder), some tree species are sometimes susceptible to an unusually severe winter. Magnolia, dogwood, tulip tree, sweet gum, red maple, birch, hawthorn, flowering cherries and plums, crape myrtles, and several oak and nut tree species like walnut and hickory.
Marginally hardy species in your region such as broad-leaf evergreens like azaleas (Rhododendron spp.), mountain laurel (Kalmia spp.), camellias, cherry laurel (Prunus laurocerasus), false holly and tea olive (Osmanthus spp.), grape holly (Mahonia spp.), English holly (Ilex aquifolium), Southern magnolia (M. grandiflora).

Prices of plants are deeply discounted in fall and sometimes worth the gamble. Adding 3-4 inches of mulch around newly set trees will trap ground heat to promote root growth and aid plant establishment. Do not fertilize newly planted trees and shrubs in the fall.

Thunderhead Japanese Black Pine For A Different Look

Posted by Hugh on September 27th, 2015

Long dense needles of ‘Thunderhead’ pine

Thunderhead Japanese Black Pine (Pinus thunbergii ‘Thunderhead’) is compact form of Japanese black pine. At maturity it may reach 20 to 25 feet high and 15 to 20 feet wide (USDA hardiness zones 5b-8). Expect this slow-growing conifer to grow 5 feet height and 4 feet width in 10 years.

By mid-winter its very long silvery candle-like buds slowly begin to emerge from terminal buds and will certainly catch your attention. Thunderhead pine frequently serves as a focal point either planted in the ground or a large container around people areas (decks and patios). It also can be developed into a privacy screen or hedge.

Japanese black pine grows in an average well-drained soil and under full sun. It exhibits exceptional drought tolerance after it’s planted for two years. Thunderhead pine is a favorite with bonsai and topiary enthusiasts who prune or sculpt this long needle conifer. Informally, its natural pyramidal growth habit is unique. No two plants look alike if left unpruned.

Thunderhead thrives along coastal areas in hot dry winds and temperatures; needles hold up to ocean salt spray and further inland to winter’s de-icing salts.

Feed with 1-2 handfuls of 10-10-10 fertilizer (or equivalent) in late winter and mulch lightly for weed suppression and soil moisture retention. Pruning is very infrequent, usually performed to reduce the candle growth in the spring. Disease and pest problems appear to be rare.

Critter-Resistant Flower Bulbs

Posted by Hugh on September 24th, 2015

“Deer Candy” Tulips

Dependable Daffodils

Who doesn’t love colorful flowering bulbs in the early spring garden? Unfortunately, many gardens are terrorized by flower-devouring deer or bulb-chomping squirrels, voles and other critters. When utilizing smelly sprays, expensive fencing, or firearms are not options, plant a wide choice of flower bulbs that critters don’t like.

Start out with long-lived daffodils, also called narcissus. They come in so many varieties, small or large flowers, and in color choices ranging from yellow, white, orange, pink, or bi-colors. Deer and rodents won’t eat them like tulips and most types of crocuses which are candy to them.

Alliums, snowdrops (Galanthus), snowflakes (Leucojum aestivum), camassia, starflowers (Ipheion), glory-of-the-snow and blue squill are also critter-proof. Deer and rodents usually leave them alone. Hyacinthoides, Scilla, Grecian windflowers (Anemone blanda) are also good bets.

Most bulbs naturalize and return to bloom for many years. Planted them in a sunny location and in well-drained soil. Encourage bulbs to naturalize by allowing the foliage to die back naturally after bloom. Do not cut back or braid foliage immediately after flowering. Leaves will store up food via photosynthesis in the new bulbs. Fertilize spring flowering bulbs in late winter with a slow-release fertilizer (Milorganite™, Osmocote™, or specially labelled bulb products).

Certain bulbs such as snowdrop (Galanthus), scilla, winter aconite (Eranthis), and snowflakes (Leucojum) are highly shade tolerant. Bulbs emerge in late winter in open deciduous shade. They receive adequate sunlight through the open deciduous woodland canopy before new tree foliage emerges by mid-spring.

Special situations: In stressful environments when animals are starving, they’ll eat almost any bulbous plant.

Best of The Critter Proof Bulbous Perennials

Ornamental onion (Allium)

Camassia

Glory of the snow (Chionodoxa).

Colchicum (late summer and fall bloomer)

Crocus tommasinianus – Squirrel-proof only

Fritillaria

Snowdrop (Galanthus nivalis)

Spanish bluebell (Hyacinthoides hispanica)

Starflowers (Ipheion)

Snowflake (Leucojum)

Narcissus (Daffodil)

Scilla

Fall Lawn And Landscape Planting Tips

Posted by Hugh on September 21st, 2015

Fall Chores At Biltmore Estates, Asheville, NC

New pansy planting in fall

The combination of warm soil and cool air makes autumn an ideal time to plant new trees, shrubs, perennials, and cool season annuals. You may want to divide certain perennials such as iris, hostas, daylilies, and lots more. Fall weather favors root growth which aids transplants to recover quickly before winter’s chill arrives.

Autumn planting tips:

1. Give plants room to grow. Don’t plant trees or shrubs too close to one another and surrounding structures (home, garage, storage buildings, utility polls). Tall trees can drop loads of leaves and twigs into roof eaves. Look up! for utility lines. Call the gas (and electric) company to locate underground lines before digging.

2. Dig planting holes that are not deep and extra wide (2 -3 times circumference) to accommodate rootballs either at or slightly above soil grade.

3. Adding soil amendments and fertilizer to the planting hole is usually not necessary. A few specific shrubs and trees are exceptions. Staking trees is usually unnecessary unless planting site is very windy.

4. Add 2-3 inches of organic-based mulches, such as pine straw (needles), wood chips or compost around base of newly planted landscape plants. Never pile mulch up around the trunk. The mulch layer offers insulation value; it traps in soil heat so shrubs and trees quickly acclimate to their new surroundings.

5. Prune off diseased, damaged or broken branches before planting.

6. Provide deer and rabbit protection if appropriate.

7. Water newly set plants the same day of planting. Do not assume that seasonal rainfall will be adequate. In some eastern U.S. states, October and November are usually drier than normal. New evergreen shrubs should be deeply irrigated. Overhead sprinkler may run for 3 hours (or 10 hours of drip irrigation) every 8 to 10 days until late November – if rainfall is not plentiful.

8. Complete new lawn seeding and/or renovating by mid-October.

8. Broadcast weed preventatives against early spring cool season weeds such as henbit, ground ivy, purslane, chickweeds, dandelions, and lots others. These weeds grow over the winter and spring months.

Six Notoriously Weak Wooded Trees

Posted by Hugh on September 18th, 2015

‘Bradford’ Pear (Pyrus calleryana) Blooming in Early Spring

Mimosa tree (Albizia julibrissin)

Almost any time is a good time to plant trees – weather permitting. Sort through many great choices and avoid planting weak wooded species. These six tree species are generally short-lived, messy, and insect and/or disease susceptible. A few may also be designated invasive in your state.

Ornamental or Callery pears (Pyrus x calleryana (‘Bradford’ and other cvs.) are popular medium sized flowering tree. In very early spring its upright branches are blanketed with white flowers. This fast growing tree develops weak branch crotches that self-destruct in stormy or windy weather. Ornamental fruits are eaten by birds that distribute the seeds. Ornamental pears may become invasive (USDA hardiness zones 4 – 8).

Silver maples (Acer saccharinium) have a short life span and a rapid growth rate compared to other large maple species. At maturity, a typical silver maple may reach up to 60-80 feet in height. Seedling types possess weak branches which tend to break in ice storms or high winds. Some improved hybrids and cultivars such as ‘Silver Queen’ exhibit a sturdier framework.

Weeping willows (Salix spp.), including corkscrew willow (S. matsudana ‘Tortuosa’), are weak wooded. During the spring and summer, willows drop lots of twig and leaf debris. Willows are susceptible to numerous disease and insect problems (USDA Plant Hardiness Zones 4b – 8).

Siberian elms (Ulmus pumila) are very large fast growing weak-wooded tree (100 feet not uncommon). They’re exceptionally messy and litter turf and ground areas year-round. As its name hints, species is extremely cold hardy, but is not heat tolerant in Southern U.S. landscapes (USDA Plant Hardiness Zones 4 – 8).

Mimosa trees (Albizia julibrissin) develop into a lovely summer flowering small tree with pink feathery flowers and fine textured foliage. Unfortunately, these summer-flowering trees are short-lived, weak-wooded, and seeds in readily from trees many miles away (USDA hardiness zones 6 – 9).

Poplars and cottonwoods (Populus spp.) grow up to 5 feet to 8 feet a year, some species reaching 40 feet to 60 feet in height. Their weak branches spread 20 feet to 35 feet apart and are dangerous to house and autos. Leaves and branches are highly susceptible to numerous diseases and insects. In rural areas poplars are often planted in rows as windbreaks along perimeters of properties (USDA Plant Hardiness Zones 3 – 9).

In summary, most quick-growing trees are weak wooded, produce lots of seeds and/or messy fruits, root sucker badly, and are disease and insect susceptible.

‘Victory’ Chosen Hosta Plant Of The Year For 2015

Posted by Hugh on September 15th, 2015

Hosta ‘Victory’

The Hosta Growers Association has selected ‘Victory’ the Hosta of the Year for 2015 (USDA Zones 3–9). ‘Victory’ is a large hosta cultivar with gold edged variegated leaves and an upright vase-shaped plant habit.

Victory hosta is a sport of H. nigrescens ‘Elatior’, distinctive also for its beautiful, upright form. Plant develops into a broad 3 – 4 feet spreading mound and around 3 feet high. Hostas rated in the “extra large” category size take 3 to 4 years to reach mature size described on plant tag.

Plants grow rapidly if properly sited and cared for. Victory hostas produce light lavender flowers that stand above the foliage on sturdy stalks. Summer flowers attract hummingbirds and some insect pollinators. Gold leaf edging tends to fade to a light cream color by late summer.

Hostas are best planted in partial to full shade and adapt to a wide range of soil types that are well-drained and generously amended with compost. One year old established plants tolerate brief spring/summer dry periods. Feed once annually with a slow-release organic based fertilizer at planting time or in early spring.

Every 5-6 years, dig up and divide hostas either when new spring growth begins to emerge or when clump shows first signs of decline in fall. Leaves on Victory hosta have thick substance that make them slug resistant.